Pigmentation phenotypes (e.g., hair color) and response to sun exposure (e.g., freckling, sunburns) have been associated with melanoma risk. However, there is also strong evidence that a combination of genotypes, endogenous physiology, and exogenous exposures influence melanoma risk. In particular, inherited genotypes involved in pigmentation pathways and response to environmental exposures (e.g., UV sun exposure) may modify an individual's risk of developing melanoma. These genes include those involved in melanogenesis, such as the melanocortin 1 receptor (MC1R), tyrosinase (TYR), the tyrosine-related proteins (TRP1, TRP2), and the P gene. Knowledge about interactions of these genes in addition to pigmentation characteristics and UV sun exposure may improve the ability to identify individuals at increased melanoma risk. This knowledge may in turn be used to target individuals for primary or secondary melanoma prevention strategies. We propose a case-control study that will directly address the complex, multifactorial etiology of melanoma that involves the interaction of genotypes involved in pigmentation pathways and other risk factors. This study will address a number of specific hypotheses. First, we will characterize candidate susceptibility genotypes. Second, we will evaluate whether genotypes are associated with pigmentation characteristics (in particular those that are associated with melanoma risk), and whether genotypes are associated with tumor characteristics, including stage, grade, and age at diagnosis., Finally, we will evaluate whether these genotypes are involved in melanoma etiology, and whether these genotypes interact with one another and other melanoma risk factors. In order to address these hypotheses, we will undertake a study using the extensive resources of the Pigmented Lesion Group at the University of Pennsylvania. The sample will consist of 1000 melanoma cases and 1000 controls. Risk factor information will be obtained by questionnaire, a DNA biosample will be collected using a non-invasive cheek swab method, and diagnostic pathology information will be collected using a systematic approach. Analyses will be undertaken to evaluate the role of candidate genotypes and other risk factors in melanoma etiology, including genotype by environment interactions.